[Fix] Issue with install button

Author: DeerajTheepshi

mode/tools/SDKUpdater/src/processing/mode/android/tools/SDKUpdater.java

@@ -32,6 +32,7 @@
 import com.android.sdklib.tool.sdkmanager.SdkManagerCli;
 
 import processing.app.Base;
+import processing.app.Messages;
 import processing.app.Preferences;
 import processing.app.tools.Tool;
 import processing.app.ui.Toolkit;
@@ -327,6 +328,12 @@ protected Object doInBackground() throws Exception {
         remotes.add(p);
       }
 
+      if (remotes.size() == 0) {
+        actionButtonPlatform.setText("Install");
+        Messages.showWarning("SDK Updater","No platform was selected");
+        return null;
+      }
+
       remotes = InstallerUtil.computeRequiredPackages(
           remotes, mRepoManager.getPackages(), progress);
       if (remotes != null) {